Artillery fire direction instrument



Feb' 9 H32- C, w. HEMEL-:Y Liw'f ARTILLERY FIRE DIRECTIQN INSTRUMENT Filed oct. 17 1927 3 sheets-sheet 1 CROSS REFERENCE yj;-

Feb. 9, 1932. C. W HENSEY 1,843,9@3

ARTILLERY FIRE DIRECTION INSTRMENT Filed Oct. 17, 1927 5 Sheets-Sheet 2 mi] M P "NG 3110er: *ce

Fei), 9, 932. Q W, HENSEY 1,843,973

ARTILLERY FIRE DIRECTION INSTRUMENT Filed OCT.. 17. 1927 3 ShefS-Shet 5 QZ l: 15.5 T

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Patented Fels.- 9, 'i932 ARTILLERY FIRE DIRRCTON INSTRUMENT Application led. October 17, 1927. Serial No. 226,603.

necting the gun position and some visible.,

point, designated the aiming point, o1' AP y an amount corresponding to a calculated angle bet-Ween the line reterred to and a line connecting the gun position and target. lewe-ver, as the target is not visible from the gun position, this angle must be calculated br data obtained observation from a point from which both the aiming point and the target are visible, this point beinsci` termed the observation point, or OP. Obviously, the angle between a line Connecting the Ol,J and the AP. and aline connectingV the OP and target T, will seldom, if ever, corrcapond eX- actly to the angle trom Al? to the gun position, (i, tothe target, T. Consequently, it becomesnecessary to go through a. series, of mathematical or graphical calculations and measurements, in order to determine the gun deflection. Added to the time required for auch calculations and the possibility ot errors or' observation and of mathematics, there is; the mechanical diilicnlty ot' performing them under stress ot battle or training conditions, and frequently in adverse weather, Without shelter.

lt is an object ot my invention, then, to provide an instrument, by means of which, through purely visual observation, or si gliting, the desired deflection angle may be ascertained in a very short time, without the necessity ot any calculation whatsoever, but purely mechanically, thus reducing to the minimum the possibility oi error, and enablingr the reading of the deflection angle direct after a simple series of mechanical steps.

It is a 'further object to provide such an in- `strinnent which may be made small in Size, `which can be used in association withv the plane table, alwaysa part ot a battery commanders equipment, and which may be readily transported by the battery com mander Without greatly adding' to his accoutrement.

Still another object is the production ot an instrument for the purposes described, the form ot' which and the manipulation of which is so simple that it can be operated by a soldier notl necessaiiiljY having the training, education and experience ot a battery conimander, or other commissioned officer, thus leaving` the battery commander tree to car-- ry ont other observations and more directly to control the tiring,` of his battery.

Still another object is the provision of such an instrument by means oi which, when desired, the range from the gun to the target can be closely estimated from the observation point.

ivvith these and other objects in view, as will be brought out in this specification, my

invention comprises the novel parts and the novel combinations thereof', all as Shown in the accompanying drawings, described in the specification, and more particularly detinedby the claims terminating the same.

In the accompanyingl drawings l have illustrated my instrument in a form which. nov.v preferred by me, and l. have diagiznn-l matically indicated the method ot its use.

ligure l is a plan view-of the instrinnent;

Figure 2 is a vertical axial section through the instrument approximately on a line perpendicular to the base line slide.

Figures 8, 4, 5 and G are diagrams'illustrating the successive steps in the use ot'the instrument.

Figures '7, S and 9 are diagrams illustrato ing the angles obtained by the sev ral steps d iagrammatically illustrated in Figures 3. 4:. 5 and A A l ln discusein;Y this invention', umlerstamt ing; thereof will be simplitied by remembering that what is done at the observation point is to reconstruct the angles as thery appear at the guns, and while the operation takes place attire observation point. the Center ot all angular measurements is the aun/s: position. inasmuch the observer irs at the obseinfatioi'i point, linear distances trom ther OP, laid out alongl lines corresponding inv direction to the lines Ol. to G (Figures 3, il,

Chl-

and ti), OP to rl", and OP to l?, will determine the direction ot' li .es from G to AP and G to T, and the desired angles may then be mel'isured. 1 5 In other Words, no angles through the GP Aare measured; directions and distances from this point are determined, and then angles can be reconstructed through the distant gun position 'to the terminal points or" these lines, and in so doingl the deflection angle desired is exactlj)7 reconstructed, and can be measured.

This comprises theestablislnnent ot' three lines, the base line connecting OP and G, the line connectingI OP and T, and the line connecting' OP and AP. With these lines laid out, and the enact location ot the points, relative to each other, determined, it becomes a simple matter to reconstruct the angle AP-G-", and to measureit. This is what my instrrment does, mechanically and by purelyv Y `al means, With the aid of a. direction finder or of ltnoivn distances and directions obtained from a inap. The establishnient the three lines is carried ont by iis f' the position of three elements, in sucon, one establishing the direction anl Lh ot' the base line, and thus fixing the `ive locations oit OP and G, the second a. li of departure in associati-.on si h ",ntion of n line from QE to "l" and the third fixing the line from OP to AP. The tvvo latter steps involve the entraining oi a member representing the lines radiating from G, for coniointY movement, iirst to T sind then to AP, whereby its angular siveep maiv be measured. This is the deflection angle. i

The basis of the instrument, then, is a base ring l adapted to be secured upon a plane table, as by the ap-ertured lugs l0, through which thumb tacks may be passed. si base ring-is provided with a central hub 11.l within which is formed a transverse slot or guide 1Q. lifithin this Iguide l2 is secured a base slide 2. An index, 13, on the hub ll, nia'v cooperate with a corresponding' scale on the bascslide 2, and this scale on the hase slide 2 may be set oli' in units representingl distances, as yards, and is intended to represent distances from the `un to the OP alongthe base line.

Carried by one end of the base slide Q is an arm 2:3. This is pivotallyv secured to the slide 30, and swings freely on this slide. i" ond arm l is pirotalli1 mounted i 'nib ll, concentric with its center ie .led an intee'ral part. ot' a LL.. Lin;

Lenni- 'e ee to pivot about the centc a' 1 tnen, is S ot the instrument. 6 It- Will assist 1n obtaining a clear understanding ot' the principles underlying and controlling the operation of the instrun'ient it' it is keptin mind that the center S represents the gun position Gr, the pivot 30 the observation point GP, and the arms 3 and Ll the lines P' or sight from Oi? and Gr, respectively. The m pivot 30, representing the OP, is otlset lfrom the center ot angular measurement, at S, but n'ieasureinents of linear distances are inade from the pivot 30, either along the slide 2 7,.,

or the arm 3, as ill he made clear hereafter. At their outer ends the two arms 3 and 4 are connected tor conjoint movement, not rigidly, but by means of a member slidable along each of the arms and formed or" two parts w swivel-et together. Thus such a member comprises the compound clip 53 and. 5e, the two parts whereof are swiveled at 50 along the median lines of the two arms 3 and e', in line with the respective centers 30 and S. rEhe ceter O' the pivot 50 represents' the crossing of the lines of sight from QP and G, at the distance from Cil represented by the setting` of 53 along the arm 3. A set screw 5 may be employed to retain the coino. posite clip in adjusted position along the arm 2E, and an index: 5l on the part cooperates ivitli a suitable scale marked on arm need not be nia oit, het, c. ire-d, it may have indications thereon of like distances, and, as will he explained hereinafter, it may be so marked that the distances 'from the gun to the target ma); be accinatelj,Y determi ed by observation iron; the observation point.

As will be apparent hereafter, means must be provided to measure the angle tl'irougli which the arm l and its ring` H-O rotate from any one select-ed position to another. lhis might be done, obviously, bj inscribing an angular scale on the l, end, employing an index on the arm fl or ring` lll), then reading the initial setting from an arbitrarv zero, cading' the second setting, and final@v determining mathematically the an gula r d'1- :terence between the tivo readings, constituting the deflection angle. However, it is highlvv desirable to avoid any mathematical calculations, and hence I have devised a means ..'hereb,7 the deflection angle maj,v he read directly, setting the zero or" the scale in the line. of departure. 'lfliis not. an absolute essential, though a iein, great convenience,

and it adds inateriallv t0 the rapidi@Y `with which such calculations een he made. and te the freedom of such calcu ions from error.

'io provide tor this, l. associate with the base l and ring' 40 a leliection rin;r G, which is journaled concentric with the ring Ll0 and hub ll. This deflection rine-A fj may mir- Yenientl),rr be supported on the base l, and be ro tative about the ringT 40, being suitably secured in place, bj' the peripheral flange mi g l i i i l l l i l itsg'uide l2 hy an amount corre 1G. The arms 3 and l swing' freely over the cooperates an index Hlll carried by the ring 40; preferably the index -ll lies in a prolon gation ot the line through the Pivotl 50 of the compound swivel niemeer and the center ot' the instrument, although it will be obvious that the 'index might be Otherwise placed and that it might he placed, in tact, on the deflection ring; and the scale carried thereby he marked instead on the ring all). However, for convenience ot measuring angles clockwise, as is always done in artillery lirel control, it is desirable that. the scale be on the deflection ring G and the index only on the ring 40.

Some suitable sighting device is carried on the arm 3 and this has been represented as the small telescope 7. r)This would usually be provided with a hair-line so that it could be laid exactly on any given object. Its axis must coincide in direction with the median line of the arm 3, that is, with the line troni the center ot the pivot 30 through the center ot the pivot 50.

The first steps in the use ot the instrument are illustrated diagrammatically in Figure 3. rhe base slide has been n'iorec within spending' to the observed or measured distance troni the gun to the Observation point. ln other words, the pivot 30 has been removed from the center point 8 ot the instrument by an amount which, on the scale carried by the slide and indicated by the index 13, equals the known or measured distance from the gun to the ohservation point. By this proceeding the distance ot the observation point from the gun has been established. Xow the direction of the base line, whose distance is thus set ott", is fixed by swinging the arm until it coincides in direction with the slide as shown in Figure 3, and then sifrhtingv through the instrument T trom the observation pointto the gun. rilhis, then, establishesthe line Oi? to G (see Figure T), and fixes the position ot the base slide 2 in the base line OP to G. The base l, theretoiore shiitable upon the plane table which supports it, is now fixed in position thereon, and must not thereafter be moved.

The present instrumenty operates in conjunction with range finder, always part ot' the battery equipment, and by the use ol' the latter instrument, it is possible to determine the distance from the OP to the tarfet T. jhet us assume that the base line, whicn has been oil, 120i) lYards, and that the distance from O lD to 'l` (Figure i) is SOOO yards. Now the distance 3000 yards, which the observed range, not from the gun to the targe but from the Oft) to the target, is set oli' alonen the arni 3, representing the line oi" sight trom OP, by means of moving the clip and 5l and clamping it with the set screw The arm 3 is new moved from coincidence with the hase slide 9. into position coinciding with a line trom OP to T, and the target is picked up through the instrument 7. This step is illustrated in Figure el. Thus, referring to Figure 8, by establishing the line U, shown in dash line, representing the angle between the slide 2 and arm 3, we have also established the line X, which in the instrument is represented by the arm d. Vile now know the angle OP to G and T, but from the gun it is desired to know the angle from AP to G to T.

Itwill not do merely to swing the arm 3 to bear on the AP, for this will not cause the arm et, represei'iting` the line of sight from G, to swing` into line with the AP, and it is this line which we wish to tix. must bring,r the range finder into operation again to determine the distance from Ol? to Ai). Now, as the arm 3 represents lines ot Accordingly, we

sight from the Ol), we set oli that distance,

say 20G() yards, on base arm 3, moving the clip member 53 to the proper position and lockinpr it with the set screw 5. low, with the clip member -l freely slidingl over the arm l, butcontroiling its angular posi ion the arin 1? is n'ioved into line from QP to and the instrument T is brought to bear on AP t" ure By this we establish the line V (Figure 9). At the saine. tin'ie, due to the entrained movement oi the arm el, we have tablished the line Y, which is the line i'roin the gun G to AI. Eis it is the angle between bl and Y which is desired (and ii we have pro vvided a means ior measuring?,r the angular sweep or" the arm el from its firstto its second position), we have determined directly the angle which is required. T his method of determination of the angle may be carried out in numerous ways, but we have found that the use oi' the detiection rin g (i entirely satisfactory. Just preceding" the final step, that is, the setting oi the distance Oi) to All) and swinging oi' the arm to bear on AP. the detlection rino' 6 brought. to a position, as shown in l ig'ure :3, where its Zero coincices with the index il on the ring Ll0, which ring 40, it will be remembered, is controlled by the position of the arm 4.

Thus the hase l had first, in eii'ect, been set to tix the first posi 'ion of the arm si., which positions arm l parallel to the line troni to 'l`.

"New, when the arm l, is brought into parallelism with tl "ie from Ul to AP, its index el will sweep '..iroug-jh an angle corresponding exactly to the detlection annie between Y and X. rl`he anguiar distance can he read then in the ancT V rlted on the le oi." the deflection ring' (i. iitable vernier scai IL on the ring` Lit) will aA ie i e.

it will be clear that so tar as absolute. measurement of angles is concerned, it will not llO inatter whether the operation illustrated in Figure il precedes that illustrated in Figure 6, or vice versa. One ot these steps could be taken, then the deflection ring set at Zero, indicating' the line of departure, then the other step lcould be taken, and the angle measured. However, owing` to the tact that in allartillery tiring data, the angle et deflection is measured clockwise from the line connecting Ol) and T, it will be necessaiw7 to follow the order given above, in order that the angle may be measured properl it it should happen that the target and aiming point should be reversed, that is to say, the target placed at the point which in the drawings is designated AP and the point designated T should be used. as the aiming point, then the angle would be measured clockwise from the line Gl? to T, around to the line OP to AP.

After the angle has been measured, ittheinstruinent is returned to the position shown in Figure Li with the distance UP to T laid ottl on the arin 3 and the arin -3 laid in line with the target, it will then he possible to read on the arin a-, if this be laid out in proper linear units, the exact range 'troni G to T.

In Figure l the position corresponding to Figure t has been indicated in solid line. and the oeiectior. ring 6 has been positioned witi a zero coincidiz e with the index el. second or last position ot the arin has been. indicated in dotted lines in Figure l, and the new position ot the index lil is indicated in dotted lines. now possible to read the deflection angle directly, and, in this case, with the deflection ring set otl in units corresponding to the plateau and drum. measureand ments ot the French 'T5 nun. held pieces, it is poss A`le to read the an 'le as plateau S and a t'action; by prcuridine` a Vernier el? on the ring' i0, the d nin reading in addition can be determined, so that it is only necessari.v to pen torni these simple operations, all purely Visual, andthe observer can immediately call ott' to the gun crew the plateau and drum reading w iich i ill place the gun on the line of the Gt' course, to malte instruments uni Yersal it is n ry that a scale be given in inils and such a scale has been indicated about the outer peripheryY ot the ring 6. The reading indicated in Figure l, then, would be 5500 mils lusf the fraction being' determined by a rerne as before.

y buch an instrument is com euieoil7 nale l of transparent Celluloid, which light. which receives the scale marking accurately. and which enables sonic readings to be c through the material itrelt', if necessary.

The nl may be located at an)Y point except at G. It may l n :trout ot, behind or proloi '1in base line :nuV either between t l? and@ or beyond the troni G. The Ol its-ell? may serre. as the A and is then t eater as in infinite prolongation of the bas e line and \\hencver the il? is located in the base line the arm ,4 is laid in prolongation ot the slide 2 `atter first laying it on T, in the manner l'irstdescribed, and moving the detlection ring to correspond with the zero inde-; il. In lieu of a visible fil), either magnetic or true north may te located, and tiring may be conducted by the inap, using the north as AP, in a manner well understood by artillery odicers. The instrument is constructed to permit av clear sweep ot G4100 mils, or a complete ci rele.

1Vliet I claim as my invention is:

".I. ln an instrument of the character de fined., including a li: se adapted t .i e lined in position, an arm so formed that one end constitutes a `ing which is inoun ed on tl e base so as to he rotaal'ile about its center, a hub in the center ot said base, the hub being supplied witli a di; e tical guide, a. slide received in the guidt necti 0' the arins out tardi): oi their centers e iii the hub. a second aLn" prrr/rally supported on the slifle so as to of swing.

'9 u an instrument ot' the character V tined, Lion. a hub in the center oi: bearii'u an angular str-.le n

angular scale providing n' including a hase be lined in p L.

base so to rotate aber' ing a zero point, an arni oi forins a ring weich is inoun o o "e so as to rotate about. the hub c r of erin bearing an index wnich e ot said arin to zero niarl: a second arin pivotall de to swingi about a cen ie center of the huh and ri neans tor pivotallj; connecting t outwardly ot their respective swing. and adjustable lengthwise arin.

relation L on the o1' each in an instrumentl ot the character defined, including a base to be tir-:ed in position, i buh in the cent1` oi said base, a hear-4 ng an angular scale rotatable through 31300 Lbout the center oi' the hub, a flianietrical ju de in said hub a id a slide received in. said ju e, a linear scale ou the slide cmnperating will an inde); on the guide, an. arin tei-niiin fr ring which rotates about the and which in cooperation rsA ring measures aucjular ningun unes oirectl, a second i piro d ported upon said slide normallyv oritv.' from the center of the hub, a linear the slide cooperating with au iur. guide, pr' siding :nec-.ns r deteru k distance of the piY etal center et sait. second arin from the pivotal center ot the tirst arni. and means i'or pivotally connecting' the arms outwardly of their respective centers ot lil swing, and adjustable lengthwise of each arm.

ll. In an instrument of the Character defined, inc-hiding?r a base to be fixed in position, a hub in the center of said base, and having a diainetrical guide, a slide guided therein, an arm terminating in a ring which is 10 tatabl)v mounted about said hub, a second arm pii'otally supported on the slide, a linear scale on said arm, and means for pivotalll'y7 connecting the ari'ns outwardly of their respective centers of swing, and adjustable lengthwise of each arin to gauge the position ot' the iirst arm While its angular deflection troni a predetermined zero point is r ad directly on the index of the ring end of the rst arm.

5. In an instrument of the character defined, a hase, a huh upstanding therefrom and having a diamet-rical guide, a slide guided therein, means whereby said base may be xed in position, with the guide extending along a known hase line, an arm terminating in a ring, and a. deflection ring, both mounted upon said base and rotatable about the center of the hub through 360, the two rings bearing a Cooperating` scale and index to enable direct readingl of angular deflection from any given position to any other, a second arm pivotalljy mounted upon the sli-flev7 at a point normally located outwardly of the eener of the hub, and means for pivotalljt7 connectingthe arms outwardly of their respective centers of swing, and ad justable lengthwise of each arni.

Signed at Seattle this Lith day of October,

CHARLES lV. HENSEY. 

